Solar iboost question

NoobSolar

Hi. I am having solar installed in a few weeks and an iboost to heat two immersion heaters on my newish cylinder, which is attached to a system boiler. I have one question - is it possible to program the iboost to ONLY use solar energy and only to work with it? I understand this is what can be done with the rather amazing Zappi car charger, and no doubt similar tech.

Merlin139

Had my Iboost for nearly 8 years. Only time it works to heat water is when spare Solar is available. I can if I so wish walk up the stairs and press a button to get it to heat if I want to waste my time and money.

My total divert through it is now just over 9.6 MW

If it does not work through spare Solar capacity then my Hot Water is heated by Gas boiler. That happens a lot between Mid Oct to Feb.

Verdigris

If you have a heat pump, can you get the i-boost to run that to heat the water. Assuming the pump heats the water tank at a COP of 2, you'd be getting twice as much heat for your sunbeams. Or am I kidding myself?

NoobSolar

Merlin- that is exactly what I want. I notice some threads from people cross with the iboost for using their mains electricity when they don't want it to - but they may have been dependent on electricity solely for heating their water. Verdigris--what an excellent question!

edwink

Noobsolar

Another one here with solar panels and an i-Boost.  It works exactly as Merlin has explained above.

HTH

2nd_time_buyer

Verdigris said:

If you have a heat pump, can you get the i-boost to run that to heat the water. Assuming the pump heats the water tank at a COP of 2, you'd be getting twice as much heat for your sunbeams. Or am I kidding myself?

For an immersion heater, it is a simple switch and element which won't begrudge being turned on and off a lot.

A heat pump will take a minute or two to get up and running. I shouldn't imagine a compressor would enjoy been cycled on and off repeatedly ever time the sun goes behind a cloud.

Edit: I over-simplified the iboost. It is not just a switch but is able to moderate the output depending on the excess power avalable (above 100w). In contrast a heat pump will either be off or on which makes it even more less suitable 

thevilla

If you're considering a Zappi at some point in the future I'd suggest you get the MyEnergy diverter rather than iboost.  I've encountered issues marrying a Zappi with a previously installed 3rd party diverter (not an iboost).

Verdigris

A heat pump will take a minute or two to get up and running. I shouldn't imagine a compressor would enjoy been cycled on and off repeatedly ever time the sun goes behind a cloud.

Good point. I'm actually looking at an intelligent controller to co-ordinate PV, ASHP, batteries and car-charger, so perhaps a solar diverter would be superfluous? Or maybe not?

2nd_time_buyer

Verdigris said:

A heat pump will take a minute or two to get up and running. I shouldn't imagine a compressor would enjoy been cycled on and off repeatedly ever time the sun goes behind a cloud.

Good point. I'm actually looking at an intelligent controller to co-ordinate PV, ASHP, batteries and car-charger, so perhaps a solar diverter would be superfluous? Or maybe not?

My thinking would be along the lines of a battery and timing the heat pump to come on early afternoon when there is a good chance of them being charged and/or good solar output.

QrizB

Would something like this help? (It might not ...)

https://www.vaillant.co.uk/homeowners/products/the-arostor-domestic-hot-water-heat-pump-96448.html

Reed_Richards

Verdigris said:

If you have a heat pump, can you get the i-boost to run that to heat the water. Assuming the pump heats the water tank at a COP of 2, you'd be getting twice as much heat for your sunbeams. Or am I kidding myself?

The simple answer is no; it cannot be done.  But even if it could you wouldn't want to because the heat pump will draw a lot of power to heat your water quickly so it can go back to heating your house.  My heat pump draws 6 to 9 kW maximum when heating the hot water cylinder and your solar panels are unlikely to give you that much power.  A 3 kW immersion heater is a much better match to typical solar panel outputs and with an iBoost you can supply less than 3 kW, whatever is spare.